2Vitamin A and Beta-Carotene Also known as retinol, retinal, retinoic acidVitamin A is found in the body in compounds known as retinoids: retinol, retinal, and retinoic acid.These have functional roles in vision, healthy epithelial cells, and growth.
3Vitamin A and Beta-Carotene Vitamin A deficiency is a major health problem in the world.Toxicity is often associated with abuse of supplements.Plant foods provide carotenoids, such as beta-carotene, some of which have vitamin A activity.Animal foods provide compounds that are easily converted to retinol.Retinol binding protein (RBP) allows vitamin A to be transported throughout the body.
5Vitamin A and Beta-Carotene Roles in the BodyVitamin A in VisionHelps to maintain the corneaConversion of light energy into nerve impulses at the retinaRhodopsin is a light-sensitive pigment of the retina that contains a protein called opsin.
7Vitamin A and Beta-Carotene Roles in the BodyVitamin A in Protein Synthesis and Cell DifferentiationThrough cell differentiation, vitamin A allows cells to perform specific functions.Epithelial cellsEpithelial tissues on the outside of the body form the skin.Epithelial tissues on the inside of the body form the mucous membranes.
8Vitamin A maintains healthy cells in the mucous membranes. Without vitamin A, the normal structure and function of the cells inthe mucous membranes are impaired.Goblet cellsFigure 11.4: Mucous Membrane Integrity.MucusStepped ArtFig. 11-4, p. 372
9Vitamin A and Beta-Carotene Roles in the BodyVitamin A in Reproduction and GrowthSperm development in menNormal fetal development in womenGrowth in childrenRemodeling of the bone involves osteclasts, osteoblasts, and lysosomes.Osteoclasts are cells that destroy bone growth.Osteoblasts are cells that build bones.Lysosomes are sacs of degradative enzymes that destroy bones.
10Vitamin A and Beta-Carotene Roles in the BodyBeta-Carotene as an AntioxidantBeta-carotene helps protect the body from diseases, including cancer.
11Vitamin A and Beta-Carotene Vitamin A DeficiencyBecause vitamin A is stored in the body, it would take a year or more to develop a deficiency in the presence of inadequate intake.Infectious DiseasesImpaired immunity correlates with vitamin A deficiency in children.The goals of worldwide health organizations include vitamin A supplementation.Night BlindnessFirst detectable sign of vitamin A deficiencyInability to see in dim light or inability to recover sight after a flash of bright light
13Vitamin A and Beta-Carotene Vitamin A DeficiencyBlindnessXerophthalmiaXerosis is the first stage where the cornea becomes dry and hard.Keratomalacia is the softening of the cornea.KeratinizationEpithelial cells secrete a protein called keratin—the hard, inflexible protein of hair and nails.Changes in epithelial cells results in keratinization, rough, dry and scaly skin.Deficiency disease is called hypovitaminosis A
16Vitamin A and Beta-Carotene Vitamin A ToxicityCan occur with concentrated amounts of the preformed vitamin A from animal foods, fortified foods, or supplements.Consuming excessive amounts of beta-carotene from supplements can be harmful.Bone DefectsIncreased activity of osteoclasts causes weakened bones and contributes to osteoporosis and fractures.
18Vitamin A and Beta-Carotene Vitamin A ToxicityBirth DefectsTeratogenic risk is possible, resulting in abnormal fetal development and birth defects.Vitamin A supplements are not recommended the first trimester of pregnancy.Not for AcneMassive doses for teens are not effective on acne.Accutane is made from vitamin A, but is chemically different. It is toxic during growth and can cause birth defects.Retin-A fights acne, the wrinkles of aging, and other skin disorders.
20Vitamin A and Beta-Carotene Vitamin A ToxicityToxicity is called hypervitaminosis AChronic toxicity symptoms include liver abnormalities.Acute toxicity symptoms include blurred vision, nausea, vomiting, vertigo, headaches, and pressure in the skull.Upper level for adults: 3000 μg/day
21Vitamin A and Beta-Carotene Vitamin A Recommendations (2001 RDA)Expressed as retinal activity equivalents (RAE) because sources include all forms of retinoids and beta-caroteneRDA men: 900 μg RAE/dayRDA women: 700 μg RAE/day
22Vitamin A and Beta-Carotene Vitamin A in FoodsRetinol is found in fortified milk, cheese, cream, butter, fortified margarine, and eggs.Beta-caroteneSpinach and other dark green leafy vegetables (chlorophyll pigment masks the color)Deep orange fruits like apricots and cantaloupeDeep orange vegetables like squash, carrots, sweet potatoes, and pumpkinWhite foods are typically low in beta-carotene.Liver is rich in vitamin A.
24Vitamin DVitamin D is a nonessential nutrient that acts like a hormone in the body.The body can make vitamin D with help from sunlight.
25(a precursor made in the liver from cholesterol) In the skin:7-dehydrocholesterol(a precursor made in the liver from cholesterol)Ultraviolet light from the sunPrevitamin D3FoodsVitamin D3(an inactive form)HydroxylationIn the liver:Figure 11.9: Animated! Vitamin D Synthesis and Activation.The precursor of vitamin D is made in the liver from cholesterol (see Figure 5-11 on p. 147 and Appendix C). The activation of vitamin D is a closely regulated process. The final product, active vitamin D, is also known as 1,25-dihydroxycholecalciferol (or calcitriol).25-hydroxy vitamin D3HydroxylationIn the kidneys:1,25-dihydroxy vitamin D3 (active form)Stepped ArtFig. 11-9, p. 377
26Vitamin D Roles in the Body Vitamin D in Bone Growth Helps to maintain blood levels of calcium and phosphorusWorks in combination with other nutrients and hormonesVitamin A, vitamin C, vitamin KParathormone and calcitoninCollagenCalcium, phosphorus, magnesium, and fluoride
28Vitamin D Roles in the Body Vitamin D in Other Roles Immune system Brain and nervous systemPancreas, skin, muscles, cartilage, and reproductive organs
29Vitamin D Vitamin D Deficiency Factors that contribute to deficiency Dark skinBreastfeeding without supplementationLack of sunlightUse of nonfortified milk
30Vitamin D Deficiency Rickets Affects mainly children worldwide Deficiency symptomsInadequate calcification of bonesGrowth retardationMisshapen bones- bowing of the legsEnlargement of the ends of long bonesDeformities of ribs,Lax muscles (resulting in a protruding abdomen) and muscle spasms
32Vitamin D Deficiency Osteomalacia Affects adults Soft, flexible, brittle, deformed bonesProgressive weaknessPain in pelvis, lower back, and legs
33Vitamin D Deficiency Osteoporosis The Elderly Loss of calcium from the bones due to inadequate synthesis of vitamin DResults in a reduced bone densityThe ElderlyDeficiency is likely due to inadequate production and activation of vitamin D, a decreased consumption of milk, and having little time in the sun.There is an increased risk for bone loss and fractures.
34Vitamin D Toxicity More likely compared to other vitamins Vitamin D from sunlight and food is not likely to cause toxicity.High-dose supplements may cause toxicity.Toxicity symptomsElevated blood calciumCalcification of soft tissues (blood vessels, kidneys, heart, lungs, and tissues around joints)Frequent urination
35Vitamin D Vitamin D Recommendations (1997 Adequate Intake) and Sources AI 5 μg/day for adults years oldAI 10 μg/day for adults years oldAI 15 μg/day for adults if older than 70 years of age
36Vitamin D Recommendations Vitamin D in FoodsFortified milk, butter, and margarineCerealsChocolate mixesVeal, beef, egg yolks, liver, fatty fish and their oils (Cod liver oil)Vegans may need fortification or supplements if they do not have adequate sun exposure.
37Vitamin D Recommendations Vitamin D from the SunSynthesized in the body from cholesterolSPF of 8 or above prevents the synthesis of vitamin D from sunlight.Can be obtained from tanning beds depending on type of UV radiation.
39Vitamin EThere are four different tocopherol compounds, but only the alpha-tocopherol has vitamin E activity in human beings.Vitamin E as an AntioxidantStops the chain reaction of free radicalsProtection of polyunsaturated fatty acids and vitamin AProtects the oxidation of LDLs
40Vitamin E DeficiencyPrimary deficiency due to inadequate intake is rareErythrocyte hemolysisOccurs in premature infantsHemolytic anemia can be treated with vitamin E.
41Vitamin E Vitamin E Deficiency - Symptoms Loss of muscle coordination and reflexesImpaired vision and speechNerve damageErythrocyte hemolysis (breaking open of red blood cells)Supplements do not prevent or cure muscular dystrophy.Fibrocystic breast disease responds to vitamin E treatment.Intermittent claudication responds to vitamin E treatment.
42Vitamin E Vitamin E Toxicity Vitamin E Recommendations (2000 RDA) Rare and the least toxic of the fat-soluble vitaminsUpper level for adults: 1000 mg/dayMay augment the effects of anticlotting medicationVitamin E Recommendations (2000 RDA)RDA adults: 15 mg/day
43Vitamin E in FoodsPolyunsaturated plant oils such as margarine, salad dressings, and shorteningsLeafy green vegetablesWheat germWhole grainsLiver and egg yolksNuts and seedsEasily destroyed by heat and oxygen
44Vitamin K Vitamin K is essential in blood clotting. Also known as phylloquinone, menaquinone, menadione, and naphthoquinoneVitamin K is unique in that half of human needs are met through the action of intestinal bacteria.Vitamin K is essential in blood clotting.deficiency can cause uncontrolled bleeding.Deficiencies can occur in newborn infants and people taking antibiotics.
45Vitamin K Roles in the Body Synthesis of blood-clotting proteins Synthesis of bone proteins that regulate blood calciumWithout vitamin K, a hemorrhagic disease may develop.Hemophilia is a hereditary disorder and is not cured with vitamin K.
47Vitamin K Vitamin K Deficiency Symptoms include hemorrhaging Secondary deficiencies may occur with use of antibiotics.Newborn infants receive a single dose of vitamin K at birth because of a sterile intestinal tract.
48Vitamin K Vitamin K Toxicity Uncommon No known toxicities High doses can decrease the effectiveness of anticlotting medications.
49Vitamin K Vitamin K Recommendations (2001 AI) and Sources AI men: 120 μg/dayAI women: 90 μg/dayVitamin K SourcesBacterial synthesis in the digestive tractSignificant Food SourcesLiverLeafy green vegetables and cabbage-type vegetablesMilk
50The Fat-Soluble Vitamins--In Summary The function of fat-soluble vitamins depends on the presence of other fat-soluble vitamins.There are many interactions of fat-soluble vitamins with minerals.It is important to eat a wide variety of foods every day.
52Antioxidant Nutrients in Disease Prevention Oxidants are compounds in the body that oxidize other compounds.Antioxidants have a role in preventing oxidation, and thus assist in the prevention of chronic disease.Researchers and medical experts are still clarifying the roles of these nutrients in relationship to health and disease.
53Free Radicals and Disease Produced by normal body processes and environmental factors such as ultraviolet light, air pollution and tobacco smokeFree radicals are highly unstable due to unpaired electrons and are often damaging.Antioxidants stabilize free radicals and protect against oxidative stress.Cognitive performance, aging, cancer, arthritis, cataracts and heart disease may be protected with antioxidants.
55Defending against Free Radicals Limiting free radical formationDestroying free radicals or their precursorsStimulating antioxidant enzyme activityRepairing oxidative damageStimulating repair enzyme activity
56Defending against Cancer Antioxidants may protect DNA.Fruits and vegetables have antioxidants such as vitamin C and beta-carotene.
57Defending against Heart Disease Fruits and vegetables strengthen antioxidant defenses against LDL oxidation.Vitamin E defends against LDL oxidation, inflammations, arterial injuries and blood clotting.Vitamin C may protect against LDL oxidation, raises HDL, lowers total cholesterol and improves blood pressure.
58Food, Supplements, or Both? Food and dietReduce saturated or trans-fatSelect foods rich in omega-3 fatty acids.Fruits and vegetables offer antioxidants among other vitamins and minerals.High in whole grains and low in refined grainsExercise, control weight and eliminate smoking to prevent disease.
59Food, Supplements, or Both? Not enough data to confirm benefits of supplements onlyContents of supplements are limitingStill need research to define optimum and dangerous levels with supplementsAt high levels, supplements may act as prooxidants.
60Food, Supplements, or Both? High-antioxidant foodsFruits – pomegranates, berries and citrusVegetables – kale, spinach and Brussels sproutsGrains – millet and oatsLegumes – pinto beans and soybeansNuts - walnuts